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Introduction to Java

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History of Java

• Java– Originally for intelligent consumer-electronic

devices

– Then used for creating Web pages with dynamic content

– Now also used to:• Develop large-scale enterprise applications

• Enhance WWW server functionality

• Provide applications for consumer devices (cell phones, etc.)

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Java Class Libraries

•Classes– Include methods that perform tasks• Return information after task completion

– Used to build Java programs

• Java provides class libraries– Known as Java APIs (Application Programming

Interfaces)

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FORTRAN, COBOL, Pascal and Ada

• FORTRAN– FORmula TRANslator

•COBOL– COmmon Business Oriented Language

• Pascal– Structured programming

•Ada– Multitasking

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BASIC, Visual Basic, Visual C++, C# and .NET

• BASIC– Beginner’s All-Purpose Symbolic Instruction Code

• .NET– .NET platform

•Visual Basic .NET– Based on BASIC

•Visual C++– Based on C++

•C#– Based on C++ and Java

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Typical Java Development Environment

• Java programs normally undergo five phases– Edit

• Programmer writes program (and stores program on disk)

– Compile• Compiler creates bytecodes from program

– Load• Class loader stores bytecodes in memory

– Verify• Bytecode Verifier confirms bytecodes do not violate security

restrictions

– Execute• JVM translates bytecodes into machine language

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Fig. 1.1 Typical Java development environment.

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Creating a Program with JCreator

•Click on the JCreator Icon

• IDE windowappears

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Creating a Program with JCreator

•Click on File, New, then Project

• Project Wizard appears– Choose Java Application template

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Creating a Program with JCreator

•Give the project a name

• Then click Next

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Creating a Program with JCreator

• You will want the JDK version 1.5

• This tab is where you can specify hsa library

At this point you can click on FinishAt this point you can click on Finish

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Creating a Program with JCreator

•Now we create our class (the program) with File, New, and Class

The Class Wizard appears. Specify a name for the class

and make sure Public is chosen

For now, you can proceed with Finish

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Creating a Program with JCreator

• The wizard creates a template.

•Now complete the program with the required commands.

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Creating a Program with JCreator

•Run the compiler with Build, and CompileFile

Build Output shows in bottom pane. This is where compiler error messages will be displayed.

Build Output shows in bottom pane. This is where compiler error messages will be displayed.

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Creating a Program with JCreator

• To run the compiled program click on Build, and ExecuteFile

• Program runs in separate window

Without Creating a ProjectWithout Creating a Project

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View Flash Presentations

•Creating a workspace, project, and application

•Writing, compiling, running an application

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11

Introduction to Java